Conventional vehicle lights have been known to include a light emitting element as a light source, and a light guide lens configured to guide light beams from the light emitting element light source. This type of vehicle light (vehicular lamp) can be exemplified as disclosed in Japanese Patent Application Laid-Open No. 2005-203111 (or U.S. Pat. No. 7,270,454B2 corresponding thereto), in particular in FIGS. 1 to 3 of the publication. As shown in these drawings of the above publication, the vehicular lamp can have a light guide lens. The light guide lens can have a central-region incidence surface and a peripheral-region incidence surface on the rear side thereof. The central-region incidence surface can be configured to allow light beams emitted from a light emitting element light source at a smaller angle with respect to the optical axis of the light source to enter the light guide lens therethrough while the peripheral-region incidence surface can be configured to allow light beams emitted from the light source at a larger angle with respect to the optical axis to enter the light guide lens therethrough.
Further, in the vehicular lamp of the above publication, the light guide lens can have a center protruding light exiting surface on the front side thereof. The center protruding light exiting surface can be spherical like a condenser lens and configured to allow the light beams entering from the central-region incidence surface and passing through the lens to exit therethrough in the illumination direction of the vehicular lamp. In addition to these, the light guide lens can have four ring-shaped reflection surfaces and four ring-shaped light exiting surfaces. The ring-shaped reflection surface can be configured to allow the light beams from the peripheral-region incidence surface to be reflected and collimated with respect to the optical axis of the light source. The ring-shaped light exiting surface can be configured to allow the light beams reflected from the ring-shaped reflection surface to pass and exit therethrough in the illumination direction of the vehicular lamp. The four ring-shaped reflection surfaces as well as the four ring-shaped light exiting surfaces can be disposed in a stepped manner.
Specifically, a description will be given of how the light beams can be guided by the light guide lens of the vehicular lamp with reference to FIGS. 1 to 3 of the above publication (in particular, FIG. 2). For example, suppose that light beams emitted from the light emitting element light source at an angle of approximately 40 degrees with respect to the optical axis of the light source may impinge on the peripheral-region incidence surface. In this case, the light beams can be reflected by the farthest ring-shaped reflection surface among the four ring-shaped reflection surfaces with respect to the optical axis, i.e., by the outermost one. Then, the light beams can exit through the farthest ring-shaped light exiting surface among the four ring-shaped light exiting surfaces with respect to the optical axis, i.e., through the outermost one.
Further, suppose that light beams emitted from the light emitting element light source at an angle of approximately 55 degrees with respect to the optical axis of the light source may impinge on the peripheral-region incidence surface. In this case, the light beams can be reflected by the second outermost ring-shaped reflection surface among the four ring-shaped reflection surfaces. Then, the light beams can exit through the second outermost ring-shaped light exiting surface among the four ring-shaped light exiting surfaces with respect to the optical axis.
Still further, suppose that light beams emitted from the light emitting element light source at an angle of approximately 70 degrees with respect to the optical axis of the light source may impinge on the peripheral-region incidence surface. In this case, the light beams can be reflected by the third outermost (or, namely, second innermost) ring-shaped reflection surface among the four ring-shaped reflection surfaces. Then, the light beams can exit through the third outermost (or, namely, second innermost) ring-shaped light exiting surface among the four ring-shaped light exiting surfaces with respect to the optical axis.
Still further, suppose that light beams emitted from the light emitting element light source at an angle of approximately 85 degrees with respect to the optical axis of the light source may impinge on the peripheral-region incidence surface. In this case, the light beams can be reflected by the nearest (or, namely, innermost) ring-shaped reflection surface among the four ring-shaped reflection surfaces with respect to the optical axis. Then, the light beams can exit through the nearest (or, namely, innermost) ring-shaped light exiting surface among the four ring-shaped light exiting surfaces with respect to the optical axis.
Accordingly, the vehicular lamp as illustrated in FIGS. 1 to 3 (in particular, FIG. 2) of the above publication can be seen as if there are four ring-shaped bright areas or light exiting surfaces when the light guide lens is observed from the illumination direction of the vehicular lamp as shown in FIG. 3 of the above publication.
Specifically, in the vehicular lamp described in FIGS. 1 to 3 (in particular, FIG. 2) of the above publication, the farthest or outermost ring-shaped light exiting surface with respect to the optical axis of the light source can be seen as being brighter by being illuminated with the light beams emitted from the light source at an angle of approximately 40 degrees with respect to the optical axis and entering the lens, because the light beams at that angle may be strong. In this case, the light exiting area of the light guide lens of the vehicle lamp may be observed as if it is enlarged.
On the other hand, the nearest or innermost ring-shaped light exiting surface with respect to the optical axis of the light source can be seen darker by being illuminated with the light beams emitted from the light source at an angle of approximately 85 degrees with respect to the optical axis and entering the lens, because the light beams at that angle may be weak. This may generate a problem of deteriorating the uniformity in illuminance of the entire vehicular lamp.